The present invention relates to a method for performing a continuous hydrosilylation reaction in a tubular reactor equipped with a stirring and plug-flow maintaining apparatus located within the reactor. The invention also relates to a method for continuous production of a modified liquid organosilicon compound.
Hydrosilylation reactions conducted in the presence of a platinum catalyst between a liquid organic compound having in each molecule at least one aliphatic unsaturated bond and a liquid organosilicon compound having in each molecule at least one silicon-bonded hydrogen atom (hereinafter referred to as SiH) are normally carried out in a batch fashion in a compatible solvent (such as ethyl alcohol, isopropyl alcohol, or a similar alcohol; or benzene, toluene, xylene, or a similar aromatic solvent). It is normally required for the above reaction that the mole ratio of the aliphatic unsaturated bonds to SiH be greater than 1 and that the coefficient of conversion (1xe2x88x92{(amount of residual SiH)/(amount of SiH prior to the reaction)}) be greater than 0.9999. In order to satisfy such requirements, the reaction often took an extremely long time.
Furthermore it is also known that the aforementioned hydrosilylation reaction is an exothermic reaction of about 40 kcal for 1 mole of SiH, and in order to prevent thermal degradation of organic groups and to maintain safety in the process, it is necessary to control the reaction temperature. Dilution with an organic solvent is often used in a batch-type production system for removal of the reaction heat. Since the use of such a solvent presents a danger from the point of view of fire or explosion, special measures have to be undertaken for the removal of the organic solvent after completion of the reaction. This decreases the efficiency of the process as a whole. It is also possible to control an increase in the reaction temperature caused by the reaction heat by dripping either a SiH-containing liquid organosilicon or a liquid organosilicon that contains aliphatic bonds to a mixture of the other of the above organosilicons containing a platinum catalyst. Such a method, however, significantly prolongs the reaction time. It has been proposed recently to conduct the hydrosilylation reaction in a tank-type reactor and then to complete the reaction by feeding the crude product to a plug-flow reactor. Such a method, however, does not solve the problems of the prior art since the process remains essentially a batch-type process.
It is an object of the present invention to provide a method for performing a hydrosilylation reaction in a speedy and efficient way without recourse to dilution with organic solvents, and without the use of a tank-type reactor. It is another object to provide a method for continuous production of a modified liquid organosilicon.
The present invention is a continuous method for performing a hydrosilylation reaction. The method comprises effecting a hydrosilylation reaction between a liquid organosilicon compound (A) having in each molecule at least one silicon-bonded hydrogen atom and a liquid organosilicon compound (B) having in each molecule at least one aliphatic unsaturated bond in the presence of a platinum catalyst (C) continuously in a tubular reactor equipped with a stirring and plug-flow maintaining apparatus located within the reactor. The invention also comprises a method for continuous production of a modified liquid organosilicon compound.